1. Field of the Invention
The present invention relates to a semiconductor device module and a semiconductor device module part and, more particularly, to such a module and a module part, including a plurality of semiconductor devices mounted on a mounting board, each device including a semiconductor element having one surface on which electrode terminals are formed, pads formed on the same surface, and wires provided at an intermediate portion thereof with a bent portion and connected by its one end to a terminal on the mounting board.
2. Description of the Related Art
A chip-sized semiconductor package (CSP), i.e., a semiconductor device which has a substantially same size as that of a semiconductor chip, has been known in the prior art, such as disclosed in U.S. Pat. No. 5,476,211. Such a known CSP is shown in FIG. 12, in which CPS 2 includes a semiconductor chip 10 having one surface, i.e., an electrode forming surface, on which are formed electrode terminals and re-wiring pads 12 to which first ends of respective wires 14 are connected. Each of the wires 14 is flexible, since it has a bent portion at an intermediate position, or portion, thereof. The other, second end 16 of the wire 14 is to be connected to a terminal on a mounting board.
FIG. 13 shows a semiconductor device module in which a plurality of CSPs 2 are mounted on the mounting board 18. The semiconductor device module shown in FIG. 13 includes a plurality of CSPs 2 each of which is connected to a pad 20, as a terminal, on the mounting board 18 via a wire 14. Connection between the wire 14 and the pad 20 is conducted by means of a solder 22.
The bent portion of the wire 14 reduces the thermal stress exerted on both the semiconductor element 10 and the mounting board 18, caused by the difference in thermal expansion coefficient therebetween. In order to allow the wire to be expanded or contracted, a space is kept between an electrode forming surface 10a of the semiconductor element 10, facing the mounting board 18, and the mounting board 18.
On the other hand, since there is a space between the surface 10a of the semiconductor element 10 and the mounting board 18, it is difficult to improve the efficiency of heat radiation from the electrode forming surface 10a of the semiconductor element 10.
Thermal conductivity of the semiconductor device module shown in FIG. 13 can be improved as compared with that of a semiconductor device module having only a space between the bottom of the recessed heat spreader 26 and the other surface 10a of the semiconductor element 10.
However, the length of the wires for connecting the respective pads 20 of the mounting board 18 to the pads 12 of the semiconductor element 10 is variable among the respective CSPs 2, 2, 2, . . . and among the same CSP 2, since the respective wires have respective bent portions. Therefore, the positions of the other surfaces 10b of the semiconductor elements 10 of the CSPs 2 mounted on the mounting board 18 are different for the respective CSPs 2 and, therefore, the thickness of the thermal conductive resin 28 filled on the other surfaces 10b of the semiconductor element 10 is variable so that the level of the thermal conductivity is different for the respective CSPs 2. Thus, a heat accumulated portion may be generated in the semiconductor device module shown in FIG. 13 and may cause error
In the CSP 2 shown in FIG. 12, the wires 14 extend upwardly from the pads 12 of the semiconductor elements 10. Therefore, during assembling process of the semiconductor device module, wires 14 of CSP 2 may interfere with the other wires 14 or other parts and may thus be damaged. The wires could be transferred together but handing of the wires would then be troublesome.
An object of the present invention is to provide a semiconductor device module and a semiconductor device module part, capable of absorbing the thermal stress caused by the difference in respective thermal expansion coefficients of a semiconductor device and a mounting board on which a semiconductor device is mounted, capable of obtaining a uniform heat radiation from the respective semiconductor devices, and affording easy assembling and handling of the semiconductor devices. To overcome the problem of improving efficiency of heat radiation addressed in paragraph 0005 above, the inventors have made an arrangement in which, in order to improve heat radiation from the other surface of the semiconductor element 10, a peripheral edges of recessed portion of a heat spreader 26 is first adhered to a surface of the mounting board 18 by means of an adhesive layer 24 and, then, a bottom of the recessed portion of the heat spreader 26 are arranged to face to the other surfaces of the semiconductor elements 10 which constitute respective CSPs 2, 2, 2, . . . , as shown in FIG. 12. In addition, the inventors filled a thermal conductive resin 28 containing fillers of non-organic material, such as alumina, silica or the others, into a region between the bottom of the recessed heat spreader 26 and the other surface of the semiconductor element 10, to improve the thermal conductivity.
According to the present invention, there is provided an apparatus for a semiconductor device module comprising: a plurality of semiconductor devices, each comprising a semiconductor element having first and second surfaces, pads formed on the first surface on which electrode terminals are also formed and curved, flexible wires having first ends fixed to the pads; a mounting board on which the semiconductor devices are mounted in such a manner that the other, second ends of the wires are connected to terminals on the mounting board; a heat spreader having a recessed inner wall provided with a peripheral edge thereof which is adhered to or engaged with the mounting board in such a manner that the second surfaces of the semiconductor elements faces to a bottom surface of the recessed inner wall; and a thermal conductive resin layer disposed between the second surface of the semiconductor element and the bottom surface of the recessed inner wall of the heat spreader, the thermal conductive resin layer having a substantially constant thickness.
The peripheral edge of the heat spreader is adhered to the mounting board by means of an elastic resin to absorb a difference in thermal expansion due to a difference in thermal expansion coefficient therebetween.
An inside region of the recessed inner wall of the heat spreader is filled with sealing resin in such a manner that the first surface of the semiconductor element is covered with the sealing resin and the wire protrudes from a surface of the sealing resin.
The thermal conductive resin layer is provided for the respective semiconductor element.
The thermal conductive resin layer is a film made of thermal conductive resin.
The thermal conductive resin layer is made of a resin containing therein fillers made of non-organic material, such as alumina, silica or the other, and/or fillers made of metallic material, such as aluminum, copper or the other.
The wire is provided at an intermediate position thereof with a bent portion.
According to another aspect of the present invention, there is provided an apparatus for a semiconductor device module comprising: a plurality of semiconductor devices, each comprising a semiconductor element having first and second surfaces, pads formed on the first surface on which electrode terminals are also formed and curved, flexible wires having one end fixed to the pads; a mounting board on which the semiconductor devices are mounted in such a manner that the other end of the wire is connected to terminals on the mounting board; a heat spreader having a recessed inner wall provided with a peripheral edge thereof which is adhered to or engaged with the mounting board in such a manner that the second surface of the semiconductor element faces to a bottom surface of the recessed wall; and a spring member having one end connected to the bottom surface of the recessed wall of the heat spreader and the other end connected to the second surface of the semiconductor element.
The spring member, having one end connected to the heat spreader and the other end connected to the second surface of the semiconductor element, is made of a part of the recessed wall of the heat spreader which is cut and drawn therefrom.
Each of a plurality of the spring members has one ends connected to the bottom surface of the inner recessed wall of the heat spreader and the other end adhered to the second surface of the semiconductor element.
The second surface of the semiconductor element is adhered to the other end of the spring member by means of an adhesive layer.
According to still another aspect of the present invention, there is provided an apparatus for a semiconductor device module comprising: a least one semiconductor device comprising a semiconductor element having first and second surfaces, pads formed on the first surface on which electrode terminals are also formed and curved, flexible wires having one ends fixed to the pads; a heat spreader having a recessed inner wall provided with a peripheral edge thereof which is to be adhered to or engaged with a mounting board; and a thermal conductive resin layer disposed between the second surface of the semiconductor element and the bottom surface of the recessed inner wall of the heat spreader.